1. Field of the Invention
The present invention relates to knitting machines, and more particularly to circular knitting machines, for example for knitting hosiery.
2. Description of the Prior Art
There have been proposed circular knitting machines having rocking selector jacks, selected ones of which are raised by a raising cam so as to raise the associated needles. The other jacks are free to move vertically within the respective grooves of the needle cylinder and in order to prevent unintentional raising of these jacks, and thus erroneous actuation of the associated needles, each of the jacks is curved along its length so that it bears against the sides of the groove. The friction produced between the jacks and the sides of the cylinder grooves acts to resist unintentional raising of those jacks which are not selected to be raised by the raising cam.
This previously proposed arrangement is, however, not entirely satisfactory at increased rotational speeds of the needle cylinder, since the friction between the jacks and the sides of the grooves leads to a heating effect, and the frictional forces are insufficient to ensure that none of the non-selected jacks are raised under the effect of the incidental forces which may arise at increased speeds.